org.optaplanner.core.impl.heuristic.move

Interface Move

All Known Implementing Classes:

AbstractMove, ChainedChangeMove, ChainedSwapMove, ChangeMove, CompositeMove, KOptMove, NoChangeMove, PillarChangeMove, PillarSwapMove, SubChainChangeMove, SubChainReversingChangeMove, SubChainReversingSwapMove, SubChainSwapMove, SwapMove, TailChainSwapMove

public interface Move

A Move represents a change of 1 or more PlanningVariables of 1 or more PlanningEntitys in the working Solution.

Usually the move holds a direct reference to each PlanningEntity of the Solution which it will change when doMove(ScoreDirector) is called. On that change it should also notify the ScoreDirector accordingly.

A Move should implement Object.equals(Object) and Object.hashCode().

An implementation must extend AbstractMove to ensure backwards compatibility in future versions.

See Also:

AbstractMove

Method Summary

Methods

Modifier and Type	Method and Description
Move	createUndoMove(ScoreDirector scoreDirector) Called before the move is done, so the move can be evaluated and then be undone without resulting into a permanent change in the solution.
void	doMove(ScoreDirector scoreDirector) Does the move (which indirectly affects the ScoreDirector.getWorkingSolution()).
Collection<? extends Object>	getPlanningEntities() Returns all planning entities that are being changed by this move.
Collection<? extends Object>	getPlanningValues() Returns all planning values that entities are being assigned to by this move.
String	getSimpleMoveTypeDescription() Describes the move type for statistical purposes.
boolean	isMoveDoable(ScoreDirector scoreDirector) Called before a move is evaluated to decide whether the move can be done and evaluated.

Method Detail

isMoveDoable

boolean isMoveDoable(ScoreDirector scoreDirector)

Called before a move is evaluated to decide whether the move can be done and evaluated. A Move is not doable if:

• Either doing it would change nothing in the Solution.
• Either it's simply not possible to do (for example due to build-in hard constraints).

It is recommended to keep this method implementation simple: do not use it in an attempt to satisfy normal hard and soft constraints.

Although you could also filter out non-doable moves in for example the MoveSelector or MoveListFactory, this is not needed as the Solver will do it for you.

Parameters:

scoreDirector - the ScoreDirector not yet modified by the move.

Returns:

true if the move achieves a change in the solution and the move is possible to do on the solution.

createUndoMove

Move createUndoMove(ScoreDirector scoreDirector)

Called before the move is done, so the move can be evaluated and then be undone without resulting into a permanent change in the solution.

Parameters:

scoreDirector - the ScoreDirector not yet modified by the move.

Returns:

an undoMove which does the exact opposite of this move.

doMove

void doMove(ScoreDirector scoreDirector)

Does the move (which indirectly affects the ScoreDirector.getWorkingSolution()). When the workingSolution is modified, the ScoreDirector must be correctly notified (through ScoreDirector.beforeVariableChanged(Object, String), ScoreDirector.afterProblemFactChanged(Object), etc), otherwise later calculated Scores will be corrupted.

This method must end with calling ScoreDirector.triggerVariableListeners() to ensure all shadow variables are updated.

Parameters:

scoreDirector - never null, the ScoreDirector that needs to get notified of the changes.

getSimpleMoveTypeDescription

String getSimpleMoveTypeDescription()

Describes the move type for statistical purposes. For example "ChangeMove(Process.computer)".

The format is not formalized. Never parse the String returned by this method.

Returns:

never null

getPlanningEntities

Collection<? extends Object> getPlanningEntities()

Returns all planning entities that are being changed by this move. Required for AcceptorType.ENTITY_TABU.

Duplicates entries in the returned Collection are best avoided. The returned Collection is recommended to be in a stable order. For example: use List or LinkedHashSet, but not HashSet.

Returns:

never null

getPlanningValues

Collection<? extends Object> getPlanningValues()

Returns all planning values that entities are being assigned to by this move. Required for AcceptorType.VALUE_TABU.

Duplicates entries in the returned Collection are best avoided. The returned Collection is recommended to be in a stable order. For example: use List or LinkedHashSet, but not HashSet.

Returns:

never null